Binding of smoothelin-like 1 to tropomyosin and calmodulin is mutually exclusive and regulated by phosphorylation

Abstract

BackgroundThe smoothelin-like 1 protein (SMTNL1) can associate with tropomyosin (Tpm) and calmodulin (CaM), two proteins essential to the smooth muscle contractile process. SMTNL1 is phosphorylated at Ser301 by protein kinase A during calcium desensitization in smooth muscle, yet the effect of SMTNL1 phosphorylation on Tpm- and CaM-binding has yet to be investigated.ResultsUsing pull down studies with Tpm-Sepharose and CaM-Sepharose, we examined the interplay between Tpm binding, CaM binding, phosphorylation of SMTNL1 and calcium concentration. Phosphorylation greatly enhanced the ability of SMTNL1 to associate with Tpm in vitro; surface plasmon resonance yielded a 10-fold enhancement in K D value with phosphorylation. The effect on CaM binding is more complex and varies with the availability of calcium.ConclusionsCombining both CaM and Tpm with SMTNL1 shows that the binding to both is mutually exclusive.Electronic supplementary materialThe online version of this article (doi:10.1186/s12858-017-0080-6) contains supplementary material, which is available to authorized users.

Retene, pyrene and phenanthrene cause distinct molecular-level changes in the cardiac tissue of rainbow trout (Oncorhynchus mykiss) larvae, part 2 – Proteomics and metabolomics

“…After 14 days, phenanthrene had in common with retene the significant depletion of smoothelin (Fig. 3), a protein found in vascular smooth muscles that has been shown to interact with calmodulin and troponin (Ulke- Lemée et al, 2017). In mammals, a deficiency in smoothelin has been associated with reduced vascular contractility, and is often observed after vascular damages (Rensen et al, 2008;van Eys et al, 2007).…”